Fluid coupling



Oct. 27, 194 2. r w. T. DUNN 2,299,883

FLUID COUPLING Filed Dec. 30 19:58

45" o E w [9 'INVENTOR BY MUM n 70mm W m,fl.z /M

A TTORNE Y5.

Patented Oct. 27, I942 2,299,883 nun coorrmo William T. Dunn, Detroit,Mich., assignor to Chrysler Corporation, Highland Park, Mich., acorporation of Delaware Application December 30, 1938, Serial No.248,369

s PATENT OFFICE A 8 Claims. (01. 60-54) 'I'hisinvention relates to powertransmission mechanism.

It pertains particularly. to power transmission mechanism in which afluid coupling of the kinetic type is used to transmit engine power tthe driving wheels of a motor vehicle.

unitary part thereoflength thereon vehicle.

ditions.

v bodiment of the invention.

Heretofore, lnmotor vehicle power transmis- Fig. 2 is a central,vertical, sectional view of sion systems employing fluid couplings,difliculty the fluid coupling used in the mechanism shown has beenexperienced by reason of the tendency in Fig. 1. of the vehicle. tocreep or drive slowly during 10 Fig. 3 is a partial side elevationalview correidling of the engine with the transmission in gear. spendingto Fig. 1, but illustrating a modification In other words, it wasnecessary in bringing the thereof. vehicle to rest, to manipulate thetransmission In the form of the invention illustrated in the intoneutral, or apply the usual brakes, to oppose drawing, the improvedfluid coupling is interposed the drive or drag transmitted through thefluid' between a vehicle engine 8 and a speed change coupling at engineidling speed, transmission 9,and comprises driving and driven It is anobject of the invention to materially portions generally indicated bythe numerals Ill reduce the aforesaid difiiculties by the provision andH respectively. The driving portion l0 comof a comparatively largecapacity evacuation prises an impeller rotor structure l2 which ischamber included within the fluid coupling as a drivingly connected asby bolts l3 to the crank- I shaft M of the engine 8.

Another object of the invention is to provide p r l rr d by the d i mmber In and an improved fluid coupling having a fluid evacuare adapted oe engaged by the usual engine ation chamber of relatively great capacitycarried starting device. by the coupling impeller, or driving member,and The driven or runner rotor member II is drivwhich is so constructedand arranged as to preingly connected to a driven shaft is whichcorreserve the compactness of the coupling assembly p s t0 the drivingShaft which O i y 6011- and maintain acomparatively small over-all nectsthe clutch of a vehicle to the transmission mechanism thereof.

By so providing a fluid coupling having its fluid In the impeller andrunner rotor structures l2 evacuation chamber fixed to the coupling im-II respectively a p ity of fluid passages peller, or fixed to thecoupling runner if. desired, are provided r ugh which the working fluid,and constituting a permanent part of the fluid circulates as is wellknown in the art. An azmucoupling, balancing operations of the couplingare lar vortex chamber I8 is shown in the drawing, facilitated inasmuchas the rotative part of the but this may be omitted withoutsubstantially afcoupling can be satisfactorily balanced as a unit, feeing the op r tion of the drive. and the coupling then installed in themotor A raised lip or baflle ll is provided on the impeller l2 for thepurpose of disrupting the flow of Another objectof theinvention is toprovide in fluid at low Sp ds 0f rotation e y increasing a fluidcoupling of this type, automatically operthe slip between the impellerand runner with able means for accommodating a rise in the fluid s qu twerin of th n y t ans t d y pressure in the working chamber thereoftotherethe former. It has been found that the baflle ll by prevent l ffluid d t heating of th fluid, has practically no eflectupon theoperation of the A further object of the invention is to, providecoupling a in m e p s and no efiect in a fluid coupling of this type, ameans for adwhatsoever at high speeds, because the fluid tends justablycontrolling the degree of evacuation deto circulate in a h loc d ouwardly of the sired for driving the vehicle under varying con b fl IIwhen he speed of rotation of the impeller increases above the idlingspeed of the A still further object is to provide in such a couorpling,automatically actuated means for retumingthe evacuated fluid to theworking chamber of the coupling at a predetermined rate, to efiectsmooth acceleration oi the vehicle.

Further objects and advantages of the invention will be apparent fromthe following detailed description of one embodiment thereof, referencebeing had to the accompanying drawing, in which:

Fig. 1 is a partial side elevational view of a motor vehicle drivemechanism illustrating one em- Starter teeth l5 are The fluid pressuregenerating portion of the impeller I2 is connected to the flywheelportion III by means of bolts i9 and has formed integrally therewith 'anouter cover housing 20 which has a rearwardly extending flange 2|.

The runner II is drivingly connected to the output shaft [6 through theintermediary of the V sleeve 23 which is provided with external splines22 and internal splines 22'. Formed on the sleeve 23 is an annularflange 24 which acts as a forward stop for the anti-friction bearingdesignated generally as 25. The bearing 25 is, of course, necessary toaccommodate the relative rotation between the impeller and the runner. Asuitable 'fluid seal 26 is provided to prevent escape of the fluidrearwardly along the sleeve 23.

A rearwardly extending sleeve 21 is journalled on the shaft l6 and hasan enlarged forward portion 29 which is provided with an integralflange, by means of which the sleeve is fixed to the impeller structureby the bolts 28.

As is apparent from Fig. 2, portion 29 of sleeve 21 is provided with aninternal shoulder which engages the rear face of seal 26, and fitssnugly against the outer race of bearing 25, thereby retaining theseparts in place. A snap ring 23' fits in a groove around the rear end ofthe sleeve 23 and prevents said sleeve from forward displacement.

The housing 28 has an open-end cylindrical member 32 secured thereto byfastening means 3|. A piston 33 is mounted within said cylinder forsliding movement relatively to said cylinder and to the sleeve 21.Piston rings 34 are provided to assist in maintaining a fluid-tightassembly.

The piston 33 is provided at its rearward end with a channeled collarportion 36 which is adapted to receive a control member as willhereinafter be described. The enlarged end portion 29 of sleeve 21affords a forward stop for the slidable piston 33, and a coiledcompression spring 31 is interposed between the piston and the flange 38of sleeve 21 to yieldingly urge the piston against the shoulder 29.

Between the housing 28 and the inner dished portion of the impellerstructure I2 is formed an annular fluid chamber 38 which is incommunication with the interior of the 'cylinder 32. A plurality ofvalves 39 are carried by the inner portion of the impeller structure andare spaced symmetrically around the circumference thereof. These valves39 control the passage of fluid from the working passages of thecoupling to the chamber 38 and vice-versa.

Each of the valves 38 comprises a pin 48 which has a threaded engagementwith the dished portion of the impeller structure and which protrudesinto the chamber 38 preferably in the general direction of the cylinderand piston assembly just described. A plurality of ports 4| are arrangedcircumferentially about the pin 48 which communicate with the chamber 38and the working passages of the impeller. A valve plate 42 is slidablymounted on the pin 48 and is yieldingly urged by the coiled spring 43 toseat upon the outer annular seat 4|. The plate 42 has a plurality ofannularly arranged ports 44 of smaller area than the ports 4| whichcommunicate with the chamber 38.

A suitable remote control, such as a pedal 45 (see Fig, 1) is providedto control the sliding movement of the piston 33. The pedal 45 ispreferably mounted in the automobile in the same location as theconventional clutch pedal for operation by the left foot of theoperator, although it may have other locations if desired.

The pedal 45 is pivotally mounted at 46 on the transmission casing andhas a bell-crank portion 41 pivotally connected to a forwardly extendingadjustable link 48; a yielding means such as the spring 43 beinginterposed between the pedal and the casing of the transmission 9 toyieldingly return the pedal to its normal illustrated position. Theforward end portion of the link 48 is pivotally connected at 50 to onearm of a bell-crank 5| mounted on the housing 52. The other arm of thebell-crank 5| extends within the housing 52 and into engagement with theshifter groove 36 of the piston 33, as shown in Fig. 2.

When pedal 45 is in the position illustrated in Fig. 1, piston 33 is inits forward position as shown in Fig. 2. It is thus obvious that thevehicle operator may move the piston 33 to rear (or right hand end asviewed in Fig. 2) of the cylinder 32 by fully depressing the pedal.

In the normal operation of the device, the coupling is filled with fluidto about three-fourths of its capacity, the fluid medium being oil,water or other suitable substance. When the engine crankshaft I4 isrotating the fluid circulates through the passages II and I2 of therunner and impeller respectively in the manner well known in the art andthe runner is driven by the circulation of pressure fluid from theimpeller.

- When the engine is idling the pressure of the circulating fluid is, ofcourse, low and the energy transmitted from the impeller to the runneris also low, consequently there is a great amount of slippage betweenthe coupler elements. It has been found however, that enough energy istransmitted to slowly drive the vehicle, if the transmission is in gear,and to cause severe clashing of the gears when changing speeds. In thisembodiment of the invention rotation of the runner may be entirelystopped at the will of the operator by fully depressing the pedal 45which thereupon moves the piston 33 to the right, as shown in Fig. 2,through the intermediary of the linkage 41, 48, 58 and 5|. This movementof the piston creates a vacuum in the chamber 38 which causes the valveelements 42 to unseat, thereby allowing the fluid in the passages and I2to be drawn into the chamber 38 at a rapid rate due to the relativelylarge increase in volume of the chamber. The withdrawal of fluid fromthe working portion of the coupling results in a sharp reduction in thetorque and/or energy transmitted to the runner and allows thetransmission gears to be shifted or the vehicle to remain at rest withthe transmission in driving position.

When the operator desires to drive the vehicle,

he releases the pedal 45 which allows the piston 33 to be returned tothe forward position (as shown in Fig. 2) under the influence of thespring 31. The initial movement of the piston produces a reversal ofpressure in the chamber 38 and causes the valve elements 42 to seatthereby cutting off the direct passage of fluid through ports 4| andcausing the fluid to return to the working passages through the smallports 44 which allows a gradual decrease in slip between elements I andI2 with consequent gradual build-up of torque in the unit resulting insmooth acceleration of the vehicle.

It is apparent from the above description that the transmission oftorque from the impeller to the runner may be interrupted at any time,at

the will of the operator, simply by depressing the pedal 45. Anotheradvantage of the arrangement lies in the fact that variation in the slipbetween the coupling elements may be obtained by partially depressingthe foot pedal, such an operation sometimes being desirable when it isdesired to proceedat anextremelyslowrate of sp while n 1 8 118 3 Fig. 3shows an embodiment of the invention that differs from that previouslydescribed in that the pedal 45 been eliminated. its funcfluid betweensaid chambers and suction means tion being performed-by the vehicleaccelerator pedal. In the flgure,; theaccelerator pedal 53,

which ispivotally mounted near its lower end on thefloor board ofthevehicle, has a bell-crank closed said elements, a fluid storagechamber carried by said driving member, passages. connecting saidchambers, cap members seatedover said passages to normally-restrlct theflowof for unseating said cap members.

i 2. In a fluid coupling, a driving element, a

driven element, a fluid circulating chamber enclosed by said elements, afluid storage chamber arm 4 r y mounted for v n therewith? 10 carried bysaid driving element, passages con- An adjustable link 4! connects arm54 with one arm of a second bell-cranktl', th'e otherarmof which has aconnection with the shifter portion 36 of the piston 33 in a mannersimilar to that shown in Fig. '2. {The spring. corresponds-to theconventional return spring that is standard on motor cars, but it may bemade somewhat stifler if necessary to assure positive action of thepiston 33. When the pedal 53 is in its illustrated dotted fluid betweensaid chambers, means responsive to a drop in pressure in said storagechamber for unseating said cap members, and means for varyingthepressure in said storage chamber.

3. In a fluid coupling having a driving element and a drivenelementwhich together enclose a fluid circulating chamber, a fluid storage lineP tion 55, the piston 33 will be withdrawn chamber carried by one ofsaid membersga pasto its rearmost position in cylinder 32 and there willbe a minimum volume of fluid in the working passages of the coupling.This is the normal position of the parts when the operator desires to'stop the vehicle or while shifting gears.

When the operator desires to accelerate the vehicle, he depresses theaccelerator, as in normal vehicle operation, and the spring 31 slowlyforces the piston 33 forwardly in the cylinder and induce a flow offluid from said clrculating chamber into said storage chamber.

4. In a fluid coupling having a driving element and a driven elementwhich together en- 32 thereby forcing the fluid back into the workclosea fluid circulating chamber, a fluid storage ing passages of thecoupling and eifecting smooth acceleration as has previously beendescribed. The linkage 8', 5|, 54 is so proportioned that the piston 33may be free to return to its exchamber carried by one of said members, apassage connecting said chambers, a cap member adapted to be seated oversaid passage to normally restrict flow of fluid between said chamtremeforward position after only 'a slightde- 35 bers, andmeans for creatingsuction in said storpression of the pedal 53, and further depression ofthe pedal will have no substantial eifect on the piston.

The improved mechanism just described also provides automaticallyoperable means for ac- 4o commodating a rise in fluid pressure in theworking chamber. In conventional fluid couplings operated underconditions requiring a high percentage of slip for sustained periods,the fluid in age chamber to thereby unseat said cap member and induce aflow of fluid from said circulating chamber into said storage chamber,said means comprising a cylinder disposed concentrically about the axisof said coupling in communication with said storage chamber, a pistonslidably disposed in said cylinder, and means for sliding said piston.

5. In ,a fluid coupling having a driving element the working chamberbecomes heated causing the and a driven element which together enclose atrapped air to expand with consequent rise in pressure. Under extremeconditions, the pressure may become high enough to force fluidpast thefluid seals and out of the coupling. This fluid circulating chamber, afluid storage chamber carried by one of said members, a plurality ofpassages connecting said chambers, said passages being circumferentiallydisposed around danger is absent in the present improved couand closelyadjacent to the axis ofsaid coupling,

pling, because the piston 33 will move toward the rear of cylinder 32 toaccommodate any increase in the pressure of the fluid in the couplingsufficient to overcome the combined pressures cap members adapted to beseated over said pas sages, springs for normally seating said capmembers, and means for creating suction in said storage chamber tothereby unseat said cap memof springs 31 and I9 (or 31 and 56 in themodibers and induce flow of fluid from said circulatflcatlon shown inFig. 3).- If it is desired to accommodate even slight increases in ,thefluid pressure, a lost motion connection maybe incorporated in theoperating linkage between the pedal and bell-crank lever 5|. making itneces- 60* transmission mechanism for drivingly. connectv sary for thepressure or spring 31 only to be overcome before permitting anincreasein the volume of the storage chamber 38.

The improved fluid coupling just described ing chamber into said storagechamber.

6. In a motor vehicle having a driving shaft adapted to be driven by themotor thereof and a driven shaft adapted to drive the vehicle, a

ing said shafts including a fluid, coupling having a fluid workingchamber therein; a throttle control member for controlling said motor;means for evacuating fluid from said working provides a mechanism whichis inexpensive, comchamber. and control means for said evacuatinB pactenough to be substituted in a vehicle in place means including linkageconnected with said throttle control member operable in responsetobemade in the above described apparatus withfluid from Said Working C be ad Operable out departing from the. scope of the invention as set forthin the appended claims.

I claim: 1. In a fluid coupling, a driving element, a

in response to initial throttle opening movement of said control memberfor gradually returning the evacuated fluid to said working chamber,

7. In a vehicle having a driven member, an

I driven element, a fluid circulating chamber en- 76 engine, and atransmission including a fluid coucontrol member on said vehicle havingmeans:

operably associated therewith tor inducing flow of fluid between saidchambers; said valves being cooperably associated with said last meansin such manner that rapid evacuation of the coupling workingnchamber isefiected upon actua tion or said control member in one direction andrelatively slow filling of said chamber is effected upon reverseactuation of said control member.

8. In a vehicle having a driven member, an

engine, and a transmission for drivingly connecting said engine and saiddriven member including a fluid coupling, driving and d iven members insaid coupling; means operable independently of the speed of said membersfor controlling the slip between said members; a-throttle control memberfor controlling said engine; means for actuating said slip controllingmeans in response to operation of said throttle control member wherebythe slip in said coupling is caused to decrease upon throttle openingmovement or said throttle control member and to increase upon throttleclosing movement of said throttle control member, and means operablyassociated with.

said slip controlling means for regulating the operation thereof inresponse to throttle opening operation of said throttle control memberas aforesaid in such manner that the slip in said coupling is caused todecrease at a predetermined rate.

WILLIAM '1'. DUNN.

